Apparatus for making circular bushings



April 13, 1937.

APPARATUS FOR MAKING CIRCULAR BUSHINGS 2 Sheets-Sheet 2 Filed Nov.` :25,1931 if '/0/ d l fm mm;

J. c. LEMMING l 2,077,335

Patented Apr. 13, 1931 APPARATUS Fon MAKING CIRCULAR BUSHINGS l John C.Lemming, Dayton, Ohio, assignor, by

mesne assignments, to General Motors Corporation, Detroit, Mich.. acorporation of Delaware Application November z5, 1931, 'serial No.577,246

5 claims. (ci. 153-49) This invention relates to .an apparatus forforming circular bushings or circular forms from iiat metal stock andhas particular reference to forming circular bearing bushings fromflatstrip bronze stock.

An object of the invention is to provide a simple and eilic'ientapparatus for producing circular bushings having uniformly exactfinished dimensions and which will have uniformly smooth and 'emcientinterior bearing surfaces.

A feature of this invention is the reduction in diameter of the bushingin the final forming operation, whereby any tendency for the formedbushing to spring open slightly at the butt joint is avoided, andwhereby such cold working of the metal improves the bearing qualities ofthe interior surface of the bushing.

Furtherobjects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred embodiment of one form of the presentinvention is clearly shown.

In the drawings:

Fig. 1 shows a fiat blank of strip bronze or other metal from which thebushing is to be formed.

Fig. 2 shows the at strip being sheared off and bent into U-form by areciprocating die. Fig. 3 shows the U-form in position between twoexterior half-dies and an interior floating arbor, just prior to thedescent of the upper halfdie.

Fig. 4 shows what'happens during the first portion of the down stroke ofthe upper halfdie. Here the bottom ends of the U-form have been bentinwardly under the floating arbor and caused saidarbor to-be raisedsomewhat to .per-- mit theends of the U-form to come together easily. f

Fig. 5 shows the completion `of the down stroke of the upper half-dieshown inFigs., 3 and 4. Here the U-form has been buckled out intoapproximately circular form by the dies and the central floating arborhas been forced to its down position' and aids in causing the bushing tobuckle out into substantially circular form though this circular form isnot exact.

Fig. 6 shows another station where the bushing is being reformed to amore exact circular form and to slightly smaller inside and outsidediameters which are its final dimensions. The dotted lines indicate theoriginal size before reforming butthe reduction indiameter isexaggerated to enable it to be shown. Here the metal of the bushingwalls is flowed slightly under the high pressure of the exteriorhalf-dies to form the bushing to exact dimensions and give themetal apermanent set. l

Fig. 7 is a section on line 'I-'I of Fig. 6 and Fig. 5 and shows thesuccessive forming operations of those two figures.

Fig. 8 is a section on line 8-8 of Fig. 6 and Fig. 5.

Similar reference characters refer to similar parts throughout theseveral views.

The drawings and vfollowing description refer to a method of makingbearing 'bushings according to this invention.

The at metal blank I is preferably sheared off from the end of acontinuous strip 9 of flat stock of bronze or vother suitable bearing"metal 4 by the edge 8 of the reciprocating die I2.. If desired, oilgrooves, holes and/or trade-marks may be stamped in the blank yIII bysuitable dies prior to the stroke of the die 'I2 which shears off blankIII. The blank I0 is then bent into the U-form II by the continueddown-stroke of the reciprocating die I2 over the stationary central dieI3. I4 is a stationary stripper bar which aids in guiding the fiat blank'I0 into proper position between dies I2 fand I3, and prevents the nextfollowing upsstroke ofv die1^I2 from dragging the U-form II up with it,all as will be clearly understood from viewing Fig. 2.

The Uform II next is passed endwise from its position on die I3 to theposition shown in Fig. 3 where 'its lower ends I5 rest by gravity uponthe curved surface I6 of the stationary lower half-die 20, the upperhalf-die 2i being at that time at a higher position than as shown inFig. 3 to provide proper clearance between it and the top of U-form II.An interior floating arbor 22 is suitably supported in the positionshown in Fig. 3 by aprojecting end shank I! (see Figs. '7

and il)y so that it may be easily moved vertically.

upward a small distance bythe ends I of the U- form II as they areforced together as *shown in Fig. 4. Floating arbor 22 has cylindricalsur faces 23, 24 and flat sides to enable it to properly clear the sidesof U-form II which at lthis timev are much closer together than the fullinside diameter of the'bushing to be formed. Now when-v vthe upperhalf-die 2l descends it compresses the U-form Il between dies 2| and 2l)and causes the lower ends yI5 of the U-form to rst cam nwardly on thesemi-cylindrical surface I6 of die 20 until they pass under the Ifreelyoating arbor 22 and raise it upwardly by buckling atthe pointsv 25, allas clearly shown in Fig. 4. From this point, further down movement ofthe upper half-die 2| rounds out the U-form II into the nearly circularform 30 as shown in Fig. 5. During this forming, the cylindricalsurfaces 23 and 24 of arbor 22 aid materially in rounding out the topand bottom portions of the U-'form Il and this causes the flat sides ofthe U-form to always and uniformly buckle outwardly rather than inwardlyeven though said ilat sides are spaced bearing qualities of bronzemetal.

other Yver'y important function of the floating arbor 22 is to preventthe formation of a raised internal bead in the formed bushing 30 wherethe two ends I of the U-form I I abut at high pressure when die 2Idescends as described above. The diameter of the circular surfaces-ofarbor 22 is preferably several thousandths of an inch less than theinside diameter of bushing 30, formed as above described, to permit saidformed bushing 30 to be easily slipped endwise from arbor 22 after theupper half-die 2| moves up again on its up-stroke. Since arbor 22 isfloating, that is, it is not held in xed position but may be movedupward freely for a short distance, the pressure of 'bushing 30 upon thelower halfdie 20 is immediately released when die 2I starts on itsupstroke and hence this feature also permits easy endwise movement ofbushing 30 from arbor 22.

For the nal forming operation shown in Fig. 6 the bushing 3D is slippedendwise from the flatted arbor 22 onto the slightly smaller but fullcylindrical arbor 42. This cylindrical arbor 42 is mounted upon a bolt43 screwed into the end of floating arbor 22 and hence arbor 42 is alsofloating (see Figs. '7 and 8). Preferably there is a small clearance 44between the central aperture in arbor 42 and bolt 43 so that arbor 42can move slightly relative to arbor 22, in order that the formingoperation of Fig. 6 will be substantially independent of that of Fig. 5even though the exterior half-dies 4U and 4I are formed integral withthe half-dies 20 and 2| as clearly shown in Figs. 7 and 8. During thisfinal forming operation of Fig. 6 all small bumps or irregularities inbushing 30' are smoothed out .and the walls of said bushing arecompressed under high pressure between the half-dies 40, 4I and thecentral arbor 40 to such an extent that the metal thereof is'ilowedslightly to cause it to permanently set in its formed exact dimensions.The cold working given the metal by the described reduction in diameterof the bushing at the station shown in Fig. 6 also improves the At thenext up-stroke of upper half-die 4I the finally formed bushing 3U isslipped endwise from the end of arbor 42 `by the movement to the left(as seen'in Figs. 7 and 8) of the succeeding bushing 30 as it is movedto its position on arbor'42. Since arbor 42 is slightly smaller indiameter than the cylindrical portion of arbor 22, bushing 30 slideseasily to its position upon arbor 42. This movement to the left (as seenin Figs. 7 and 8) of both bushings 30 and 3| is done by automatic meansknot shown since it form no essential part of this invention.

It is to be understood that the operations described above preferablyare continuous, that is,

the U-form II'is made at one station, the initial forming of bushing 30is done at a second station,

and the final forming of bushing 30' is done at a third station, all atone down stroke of the punch press carrying the dies correspondingl tothese three stations.

The bushings coming from the third station,4

that is, from arbor 42 may later have their' ends cut smooth orchamfered in a suitable trimming machine if it is so desired, butotherwise these bushings are ready to be mounted as bearings in themachine in which they are to be used.

While the form of embodiment of the present invention as hereindisclosed, constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claimswhich follow.

What is claimed is as follows:

1. Apparatus for making a circular bushing from a U-form metal blankcomprising: two relatively reciprocating dies have coacting formingcavities which engage and compress said Uform blank therebetween andforce same to buckle outwardly into circular form, and a flattenedfloating arbor positioned between said coacting cavities and having suchcross section dimensions that said U-form blank may be passed thereaboutprior to its being formed into circular shape, said floating arborhaving surfaces which engage portions 0f the inside surface of thebushing as said cavities which engage and compress said U-form blanktherebetween and force same to buckle outwardly into circular form, anda flattened floating arbor located within said die cavities when inclosed position and having parti-cylindrical surfaces which engage theinside surface of the bush.- ing while it is being formed into circularshape.

3. Apparatus for making a circular bushing from a U-form metal blankcomprising: two relatively reciprocating dies having coacting formingcavities which receive and compress said U-form blank therebetween andbend same into circular form, and a flattened central arbor havingdiametrically opposed parti-cylindrical surfaces which engage portionsof the inside surface of the bushing being formed, said arbor having asectional width less than its dimension across said parti-cylindricalsurfaces whereby it may lie freely within said U-form blank prior to itsbending into circular shape.

4. In an apparatus for making a circular bushing from a U-form metalblank,`in combination, two relatively reciprocating dies having coactingsubstantially semi-cylindrical forming cavities which engage andcompress said U-form blank.

therebetween and force same to buckle out-l wardly into substantiallycylindrical form, and a floating arbor positioned between said coactingdies and having a width materially less than the inside diameter of thebushing to be formed so that said U-form blank may pass thereabout priorto its being buckled outwardly by 'said coacting dies.

5. In an apparatus for making a circular bushing from a U-form metalblank. inv combination, two relatively reciprocating dies havingcoacting substantially semi-cylindrical forming cavities which engageand compress said U-form blank therebetween and force same to'buckleoutwardly into substantially cylindrical form, and a floating arborlocated between said coactingv dies and movable relative to both of saiddies to permit the opposed ends of said U-form blank to pass therearoundwhile being bent into circular shape, said arbor having a widthmaterially less than the inside diameter of the bushing to be formed andI JOHN C. LEMMING.

